MXieuicanJAuscum - American Museum of Natural History

26 AMERICAN MUSEUM NOVITATES
NO. 1965
Indian Ocean forms identified as F. lacinziatutm by Alcock (1898), contending
that Duncan's (1873) usage of F. laciniatum [F. laciniatum=
U. arcticus] was correct and that Alcock had been led astray by Duncan's
illustrations. He further showed that Lindstrom's judgment was in
error in regard to the affinities of F. alabastrum. Marenzeller founded
F. chunii on the species identified as F. distincturn by Duncan (1873),
an unnecessary maneuver. Marenzeller named F. stabile as a new
species for the reception of specimens from the Cape Verde Islands.
Vaughan (1907) followed Marenzeller's interpretation of F. laciniatutm
and reunited F. chunii and F. distinctum. Gravier (1920) utilized
three names for specimens in his collections: F. alabastrum, F. distincturm,
and F. deludens.
Typical F. alabastrum has a roughly triangular distribution, the
apex lying on the western shores of the Atlantic in the area between
Chesapeake Bay and Cape Cod, with the base extending from the Cape
Verde Islands to northern Norway. Over most of this area it is found
at depths below 1000 meters. Flabellum rnoseleyi is a variation of the
typical form, having a more nearly circular calice, and a conical pedicel
of greater length than that of F. alabastrum. It has a distribution
within the West Indies. Flabellum braziliensis and its synonym
F. stabile seem also to be closely allied with F. alabastrum, differing
only in the lesser expansion of the calice of the latter and the thickening
of the proximal edges of the septa to form a pseudocolumella in
the former. This variety is found in the equatorial region of the
Atlantic.
Flabellum distinctum is apparently confined to the eastern Atlantic
and is generally found in shallower depths than F. alabastrum. Flabellum
angulare, F. apertum, and F. arcticus seem to be closely related,
although the last is not well-known. Flabellum angulare has a smoother
wall than F. arcticus and may represent a distinct variety. It has a
western Atlantic distribution, while F. arcticus is found in the eastern
Atlantic. Flabellum macandrewi is known to me only by Gray's (1849)
figure. On the basis of the poor illustration I cannot recognize it, so
follow other authors in tentatively assigning it to F. arcticus. Flabelltrn
deludenis Gravier apparently belongs with the F. arcticuis group, although
the calice is much more open.
These varieties may well be a series of geographic variants and
eventually be recognized as subspecies. Work that is now in progress
must be finished before the distribution of the various types can be
(letermine(l.